Materials Science · Cross-listed from physics.med-ph
The FLASH enigma
Diana Shvydka, Victor Karpov and Nilendu Gupta
We consider physics behind the FLASH modality of cancer radiation treatment where extremely short treatment times are achieved with ultra high dose rates maintaining the conventional antitumor effectiveness and yet substantially reducing damage to normal tissues (sparing effect). The difference in responses between normal and tumor tissues is attributed here to different recombination rates related to their structure morphologies: ordered in normal vs disordered in the tumor tissues. Correspondingly different are their charge densities under ionizing radiation. In normal tissues it is high enough to form electron-hole
liquid (EHL). Because of low EHL diffusivities, the chemical reaction and generation of free radicals are suppressed; hence, sparing effect. To the contrary, a disordered tumor tissue renders efficient energy relaxation channels forming antitumor free radicals. We describe the FLASH thresholds for doses and dose rates.
Read the full abstract ▾
Materials Science
Tuning the optoelectronic properties of graphene quantum dots by BN-ring doping: A density functional theory study
Samayita Das and Alok Shukla
Graphene monolayer is a material with zero band gap, because of which its applications in optoelectronics are limited. The question arises, can we modify the optoelectronic properties of
graphene by doping it with other atoms? Synthesis of 2D monolayer of
graphene doped with hetero-atoms such as boron and nitrogen, and a few computational studies of their structural and electronic properties were previously reported. In this work, we aim to answer this question for
graphene quantum dots (GQDs) by replacing their carbon rings with $(BN)_3$ (borazine) hexagonal rings. We have studied in detail the geometry, electronic structure, and optical absorption spectra of fourteen different borazine-ring doped diamond-shaped GQDs using first-principles density functional theory (DFT). These BN-GQDs differ in the location, orientation, and the number of borazine rings. We computed their optical absorption spectra using time-dependent DFT (TDDFT) and examined: (a) for single-ring doped BN-GQDs the influence of ring location on optical properties, and (b) for double-ring doped systems, the influence of location, mutual distance and orientation of the rings on their absorption spectra. Frontier molecular orbitals are studied in detail to understand the nature of low-lying optical excitations. We also performed a group-theoretic analysis of the influence of their reduced
symmetries on their optical properties. Our results indicate that BN-ring doping can achieve significant control over the optical properties of GQDs. The comparison of the optical absorption spectra of the BN-GQDs with the parent GQD shows remarkable spectral broadening with optical gap spanning over infrared to visible region. Thus, systematic BN-ring doping provides easy tunability of the electronic and optical properties of BN-GQDs, which is very promising for optoelectronic applications.
Read the full abstract ▾
Soft Condensed Matter
Condensate-mediated shape transformations of cellular membranes by capillary forces
Lukas Hauer, Katharina Sporbeck, Joseph F. McKenna et al. (+5 more)
Phase-separated biomolecular condensates with
liquid-like properties play a key role in the organization and compartmentalization of the intracellular environment. Condensate-mediated capillary forces acting on membranes drive physiologically important reshaping of membrane-bound organelles, such as vacuoles and autophagosomes. Here, we explore condensate-mediated membrane shape transformations. We employ {in planta} live-
cell imaging, an in vitro reconstitution system with tunable interfacial tension, and computer simulations of an elastic membrane model to describe three morphologies of membrane structures localized at condensate interfaces: tubes, sheets, and cups. We find that the forces associated with high interfacial tension drive the formation of stable sheets, while tubes and cups prevail at lower interfacial tension. We calculate the free energies of each membrane shape and identify the energy barriers that govern the transitions between the shapes. With this approach, we find that shape transformations depend on the history of the interfacial membrane and exhibit a tube-to-cup hysteresis. These findings indicate that temporal control of condensate surface properties can mediate the morphogenesis of cup-like structures in
cells, such as the formation of "bulbs" within plant vacuoles. Our results further generalize how the interplay of condensates and membranes contributes to intracellular organization.
Read the full abstract ▾
All authors Lukas Hauer, Katharina Sporbeck, Joseph F. McKenna, Dmytro Puchkov, Alexander I. May, Lorenzo Frigerio, Roland L. Knorr, Amir H. Bahrami
Soft Condensed Matter · Cross-listed from nlin.CD
Dicovering the emergent nonlinear dynamics of acoustically levitated cube clusters
Annie Z. Xia, Melody X. Lim, Jason Z. Kim et al. (+2 more)
The complex behavior of many natural and engineered systems emerges from the interaction of a small number of effective degrees of freedom. Discovering the physical basis of the interactions between these degrees of freedom directly from experimental observations has been a longstanding challenge, particularly with respect to predicting the long-time dynamics of dynamical systems with unknown equations of motion. Here, we introduce a data-driven approach that is able to produce a generative model for the long-time dynamical behavior of systems with a weakly attracting
manifold. We apply this method to an experimental dynamical system with two degrees of freedom: acoustically levitated pairs of cube-shaped particles, which cluster by sharing a single edge. In the acoustic trap, the center-of-mass of the cube cluster oscillates vertically about the levitation plane, while also oscillating about their flexible hinge-like connection. Depending on their initial condition, the hinge dynamics evolve about three distinct nonlinear dynamical attractors persisting for hundreds of cycles. In order to capture the underlying physics, we develop a numerical fitting procedure and extract a minimal nonlinear dynamical model that captures both the long-time dynamics of the cluster as well as the convergence onto the dynamical steady state. This dynamical model uncovers the nonlinear, non-reciprocal coupling between the center-of-mass motion and the hinge degree of freedom that stabilizes the dynamical attractors, which we subsequently confirm by independent finite-element methods. Our results demonstrate a novel data-driven method for the discovery of nonlinear models with long-timescale stable predictions.
Read the full abstract ▾
All authors Annie Z. Xia, Melody X. Lim, Jason Z. Kim, Bryan VanSaders, Heinrich Jaeger
Mesoscale and Nanoscale Physics
Flexural Cavity Mechanics in Electrostatically Driven 1D Phononic Crystal
Vishnu Kumar, Bhargavi B.A. and Saurabh A. Chandorkar
Phononic
Crystals provide a versatile platform for controlling
phonons in applications such as waveguiding, filtering, and sensing. To minimize dissipation, cavity resonators are often embedded within the bandgap of phononic
crystals and integrated with suitable transduction techniques. Here, we demonstrate one-dimensional (1D) phononic transmission using electrostatic transduction, enabling the realization of high-quality mechanical oscillators. Using a double-ended tuning fork resonator embedded in a 1D phononic
crystal, we observe degenerate flexural modes (in-phase and out-phase) exhibiting enhanced and comparable quality factors within the same device due to mode degeneracy. The in-phase mode, whose frequency lies inside the phononic bandgap, shows an approximately two-fold increase in quality factor compared to an anchored resonator, while this enhancement diminishes for the out-phase mode (frequency outside the bandgap) at temperatures where thermoelastic dissipation is negligible. This approach offers a promising route toward low-loss, encapsulated phononic devices for sensing and signal processing applications.
Read the full abstract ▾
Superconductivity
Taming the expressiveness of neural-network wave functions for robust convergence to quantum many-body states
Dezhe Z. Jin
Neural networks are emerging as a powerful tool for determining the
quantum states of interacting many-body fermionic systems. The standard approach trains a neural-network ansatz by minimizing the mean local energy estimated from Monte Carlo samples. However, this typically results in large sample-to-sample fluctuations in the estimated mean energy and thus slow convergence of the energy minimization. We propose that minimizing a logarithmically compressed variance of the local energies can dramatically improve convergence. Moreover, this loss function can be adapted to systematically obtain the energy spectrum across multiple runs. We demonstrate these ideas for
spin-1/2 particles in a 2D harmonic trap with attractive Poschl-Teller interactions between opposite
spins.
Read the full abstract ▾
Materials Science
Assessing the suitability of the Thomas-Fermi-von Weizsäcker density functional for itinerant magnetism
Bishal Thapa, Phanish Suryanarayana and Igor I. Mazin
We assess the ability of the Thomas–
Fermi–von Weizsacker (TFW) functional within orbital-free density functional theory (DFT) to describe itinerant magnetism.
Magnetic stability is evaluated through the susceptibility obtained from the second derivative of the total energy with respect to the net magnetization. Calculations are performed for the paramagnetic metals Al and Pd and the canonical ferromagnets Fe, Co, and Ni, with the results benchmarked against Kohn–Sham DFT. The orbital-free results show poor agreement with the Kohn–Sham predictions, failing to capture even the qualitative trends. Using the orbital-free ground-state density with the Kohn–Sham functional in a non-self-consistent calculation yields reasonable qualitative agreement, although the quantitative agreement remains limited. These results highlight fundamental limitations of the TFW functional for describing itinerant magnetism.
Read the full abstract ▾
Mesoscale and Nanoscale Physics
Dissipation effects in the Su-Schrieffer-Heeger model coupled to a metallic environment
Leandro M. Arancibia, Cristián G. Sánchez and Alejandro M. Lobos
We theoretically study the electronic and
lattice properties of a trans-polyacetylene (tPA) molecule deposited on top of a metallic substrate at
equilibrium. We describe the system using a modified Su-Schrieffer-Heeger (SSH) model generalized to incorporate the effects of a metallic environment, represented by independent one-dimensional semi-infinite chains coupled to each site of the SSH chain (i.e., “local bath approximation"). We focus on the zero-temperature case and obtain the physical properties of an $N$-site tPA chain deposited on a metallic surface by minimizing its total ground-state energy (i.e., electronic plus
lattice degrees of freedom) as a function of the $N$
lattice-site positions. Interestingly, in the case of a homogeneous metallic substrate, where all coupling parameters are assumed identical, the SSH chain undergoes a zero-temperature
insulator-to-metal transition as the coupling parameter $\gamma_0$ reaches a critical value where the Peierls dimerization is fully suppressed and the system becomes metallic. In addition, our model can be generalized to describe inhomogeneous situations where the substrate contains metallic and insulating regions, as usually occurs in realistic experiments containing accidentally oxidized decoupling layers. In this case, our results predict the occurrence of local nucleation of the metalized or the Peierls-dimerized phase within the same tPA molecule, depending on whether the surface directly beneath the molecule is metallic or insulating, respectively. We finally discuss the relevance of our findings for both the correct interpretation of existing tPA/Cu(110) experiments, as well as for their possible utility in the design of novel organic nanoelectronic devices.
Read the full abstract ▾
Strongly Correlated Electrons · Cross-listed from quant-ph
Quantum simulation of lattice gauge theories coupled to fermionic matter via anyonic regularization
Mason L. Rhodes, Shivesh Pathak and Riley W. Chien
The optimal regularization of infinite-dimensional gauge-field degrees of freedom is a central open problem in the simulation of
lattice gauge theories on
quantum computers. Here, we consider regularizing the gauge field by replacing the gauge group $G$ with a braided fusion category whose objects correspond to Wilson lines of the associated Chern-Simons theory $G_k$, with the level $k$ serving as the regularization parameter. We demonstrate how to couple these regularized gauge groups to fermionic matter using the framework of fusion surface models, which treats matter and gauge field excitations as interacting anyons. We then address the simulation of the regularized
Hamiltonian, in the Kogut-Susskind formulation, on fault-tolerant
quantum computers. We provide explicit
quantum circuit constructions for implementing the primitive gates in this model, the $F$ and $R$ symbols, for $U(1)_k$ and $SU(2)_k$ anyon theories.
Read the full abstract ▾
Mesoscale and Nanoscale Physics · Cross-listed from quant-ph
Role of spectral structure in adiabatic ground-state preparation of the XXZ model
Francisco Albarrán-Arriagada and Juan Carlos Retamal
Adiabatic ground-state preparation is fundamentally limited by the spectral structure of the time-dependent
Hamiltonian, particularly by gap reductions and degeneracies that induce nonadiabatic transitions. We examine this dependence in the anisotropic Heisenberg (XXZ) model on an eight-site ring by comparing three strategies: optimization of the initial
Hamiltonian, addition of auxiliary terms, and considering approximate counterdiabatic driving. Owing to anisotropy-dependent level crossings among low-energy states, the XXZ model provides a stringent
benchmark. We find that performance is mainly constrained by spectral degeneracies between the ground and excited states. Simple strategies such as initial-
Hamiltonian optimization or site-dependent Zeeman fields, suppresses critical crossings and drastically enhance ground-state preparation. In contrast, counterdiabatic terms alone do not improve the protocol when the spectral structure remains level-crossings, becoming effective only after degeneracies are removed. These results identify spectral engineering as a prerequisite for efficient adiabatic ground-state preparation in interacting
spin systems.
Read the full abstract ▾
Strongly Correlated Electrons
Magnetic Imaging of Macroscopic Spin Chirality Flipping
H. Miao, G. Fabbris, J. Bouaziz et al. (+12 more)
Chirality is a fundamental organizing principle of correlated and topological states. In
quantum magnets, chirality arises from the
geometric twisting of
spins and serves as an emergent source of Berry
curvature and
quantum metrics. Although external fields can reversibly tune the
spin chirality, understanding how spontaneous reversal occurs on macroscopic length scale remains an unresolved challenge. In this letter, we use resonant
magnetic x-ray scattering with 2.5-micron spatial resolution to image intertwined
spin, charge, and
lattice orders of the correlated topological magnet EuAl4. We uncover a macroscopic chirality flipping transition and a remarkable
chiral memory effect. The
chiral magnetic domain tracks the landscape of the underlying charge density wave, implicating emergent
chiral magnetic interactions arising from competing
chiral and nematic
lattice fields. Our results reveal the fundamental significance of magnetoelastic coupling in stabilizing homochiral and topological
magnetic states.
Read the full abstract ▾
All authors H. Miao, G. Fabbris, J. Bouaziz, W. R. Meier, P. Mercado Lozano, Y. Choi, J. Strempfer, D. Haskel, S. Blügel, M. Cook, M. Brahlek, H. N. Lee, A. D. Christianson, A. F. May, S. Okamoto
Strongly Correlated Electrons
Hubbard model at U=$\infty$: Role of single and two-boson fluctuations
Debanand Sa and Anirban Dutta
We have developed a semi-analytical framework formulated in the canonical
fermion representation to investigate strongly correlated electron systems. We consider the U=$\infty$ Hubbard model and used the equation of motion method to calculate the
fermion self-energy which has two parts: single and two-
boson exchange processes. The emergent
bosons here are self-generated local charge and
spin-density fluctuations which become strongly time-dependent due to extreme correlations. The computed
boson spectral density is a diffusive damped mode with a long tail. The electron self-energy at $d=\infty$ is computed self-consistently. The corresponding fermionic spectral density displays a pronounced coherence peak at $\omega=0$, while its frequency derivative develops a two-peak structure at finite $\omega$. The resistivity shows a linear temperature dependence over a broad range, crossing over to coherent
Fermi-
liquid behavior at extremely low temperatures.
Read the full abstract ▾
Mesoscale and Nanoscale Physics
Tailoring spontaneous symmetry breaking in engineered van der Waals superlattices
Keda Jin, Lennart Klebl, Zachary A. H. Goodwin et al. (+5 more)
Superlattice engineering in van der Waals
heterostructures (e.\,g.\ by moiré engineering) provides a powerful platform for designing electronic bands and realising correlated and topological
quantum phenomena. Here, we pioneer a scheme to tailor superpotentials based on intrinsic substrate electronic orders. We show that this establishes a robust, self-aligned, and highly versatile route to band-structure control as we demonstrate in
graphene by engineering two distinct, nearly commensurate superlattices using the charge density waves of 1T-NbSe$_2$. In these superlattices the
graphene's Dirac cones are folded either to the $\Gamma$-point or to the K-points of the mini-Brillouin zone. Using scanning tunnelling microscopy, we observe that the $\Gamma$-folded system preserves C$_3$
symmetry, while the K-folded system exhibits spontaneous
symmetry breaking. Combining density functional theory with an interlayer interaction model, we reveal that this difference is not electronically driven but originates from a structural instability. Our work establishes superlattice engineering for designer
quantum states and unveils a structural mechanism for controlled emergent
symmetry breaking.
Read the full abstract ▾
All authors Keda Jin, Lennart Klebl, Zachary A. H. Goodwin, Junting Zhao, Felix Lüpke, Dante M. Kennes, Jose Martinez-Castro, Markus Ternes
Soft Condensed Matter · Cross-listed from physics.bio-ph
Biomedical active matter: Emergence and breakdown of collective functionalities
Arnold Mathijssen, Hamed Almohammadi, Lauren Altman et al. (+13 more)
Living systems are made of active materials with microscopic components that work together to perform macroscopic biological tasks. The breakdown of these collective functionalities leads to diseases, which, conversely, could be treated by exploiting self-organization in healthcare technologies. Here, we review recent advances in this rapidly growing field of biomedical active matter. The main themes are (1) collective self-assembly and spatiotemporal coordination; (2) collective motion, transport, and
navigation; (3) collective sensing, signaling, and communication; and (4) collective adaptation,
evolution, and learning. We discuss these emerging processes in a wide range of systems, including
protein folding, biomolecular condensates, cytoskeleton dynamics, intracellular flows, bacterial biofilms, quorum sensing, cilia synchronization, wound healing, biolocomotion,
neurons, endocrine signalling, and cardiovascular flow networks. For each, we highlight medical conditions associated with reduced collective functionality and how they may be treated using microrobotic swarms, bioinspired metamaterials, diagnostics, lab-on-chip devices, organoids, and other active and adaptive matter innovations.
Read the full abstract ▾
All authors Arnold Mathijssen, Hamed Almohammadi, Lauren Altman, Talia Calazans, M. J. Ferencz, Michelle Fung, Ian J. Lee, Maciej Lisicki, Ivy Liu, Maggie Liu, Tianyi Liu, Ernest Park, Ran Tao, Albane Thery, Zeyuan Wang, Margot Young
Materials Science
Synthesis and Transfer of Freestanding Strain-Engineered Vertically Aligned Nanocomposite Thin Films
Carlos Rodríguez Cortéz, Moussa Mebarki, Bruno Berini et al. (+11 more)
The recent development of freestanding
oxide thin films opens up exciting opportunities for the design of novel
heterostructures with enhanced functionalities. Here, we explore the fabrication of membranes consisting of dense arrays of ultrathin CoxNi1-x nanowires epitaxially embedded in a SrTiO3
matrix. Through combined x-ray absorption spectroscopy, x-ray resonant
magnetic scattering, x-ray diffraction and magnetooptical experiments, we show how a SrVO3-mediated lift-off process can be used to create and transfer these membranes while simultaneously preserving the structural and chemical integrity of the self-assembled, metallic CoxNi1-x nanopillars. With this approach, the large axial deformation of the embedded nanostructures is kept intact and, as a direct consequence, the
magnetic properties of the nano-composite thin films remain largely unaltered after substrate removal. Our findings thus highlight a novel route for the synthesis of freestanding, strain-engineered vertically aligned
heterostructures and pave the way for their future integration into spintronic and optomagnetic devices.
Read the full abstract ▾
All authors Carlos Rodríguez Cortéz, Moussa Mebarki, Bruno Berini, Dominique Demaille, Vincent Polewczyk, Yunlin Zheng, Pal Bhuyan, Boris Vodungbo, Emmanuelle Jal, Horia Popescu, Nicolas Jaouen, Yves Dumont, Marcel Hennes, Franck Vidal
Statistical Mechanics · Cross-listed from quant-ph
Consistent monitoring of quantum fluctuations
Xiangyu Cao
Recent works on the decoherent histories formalism suggested that slow-evolving macroscopic quantities (extensive sums of local observables) in
quantum many-body systems can be consistently monitored: The existence of past measurements does not alter future outcome distribution. Here, for Gaussian weak measurements, we show that fluctuations of macroscopic quantities cannot be consistently monitored in general, in contrast to their intensive mean value. Exceptions include fluctuations at infinite temperature, at critical points, and in semiclassical systems. We analytically quantify non-consistency in terms of susceptibility, and obtain related results on
entropy growth under noisy
unitary.
Read the full abstract ▾
Quantum Gases
Ising criticality can drive vortex deconfinement in a spin-orbit coupled Bose gas
Stuart Yi-Thomas, David M. Long and Jay D. Sau
Spin-orbit coupling in Bose gases is known to lead to an Ising-
symmetry-broken phase where the
bosons condense at one of two nonzero momenta. In two dimensions, the finite momentum of the order parameter allows
vortex-antivortex pairs that are typically bound in the superfluid phase to freely separate along Ising domain walls. This non-trivial interaction between the superfluid and the Ising order suggests that the critical fluctuations near an Ising transition could drive a Berezinskii-Kosterlitz-Thouless transition of the superfluid. We present numerical evidence of this phenomenon using a Monte Carlo simulation that shows the disappearance of superfluid stiffness near an Ising transition. Additionally, we find numerical evidence that the Ising phase transition becomes first order and we justify this claim with a variational approximation.
Read the full abstract ▾
Strongly Correlated Electrons
Unified gauge-theory description of quantum spin liquids on square-based frustrated lattices
Atanu Maity, Andreas Feuerpfeil, Ronny Thomale et al. (+2 more)
Quantum spin liquids are commonly thought to be highly sensitive to
lattice geometry,
symmetry, and microscopic exchange patterns, leading to a proliferation of seemingly distinct phases across frustrated magnets. Here, we provide a framework that unifies phases that appear distinct from the viewpoint of this intuition. We postulate that the
spin-$\tfrac{1}{2}$ Heisenberg antiferromagnets on the square, Shastry-Sutherland, and checkerboard
lattices can realize a single unified
quantum phase: a gapless $\mathbb{Z}_2$ Dirac
quantum spin liquid, despite their markedly different
lattice symmetries. Using a systematic projective
symmetry group analysis, we identify a checkerboard
spin-
liquid state that completes a closed set of adiabatically connected phases linking the well-established square-
lattice and Shastry-Sutherland
spin liquids. Crucially, we show that this
lattice-level unification is mirrored exactly in the continuum description. In all three cases, the
spin liquids descend from a common SU(2) $\pi$-flux parent state and are governed by the same gauge theory, QED$_3$ with two Dirac
fermion flavors coupled to two adjoint
Higgs fields. As a result, we postulate that the surrounding Néel and valence-bond-solid phases and their confinement transitions admit a unified interpretation within the framework of deconfined
quantum criticality. More broadly, our results suggest that
quantum spin liquids are most fundamentally classified not by
lattice geometry or microscopic couplings, but by the emergent gauge theory and its
Higgs structure. Distinct frustrated
lattices can thus host the same
quantum phase and exhibit the same confinement mechanisms, despite substantial differences in their microscopic
symmetries.
Read the full abstract ▾
All authors Atanu Maity, Andreas Feuerpfeil, Ronny Thomale, Subir Sachdev, Yasir Iqbal
Disordered Systems and Neural Networks · Cross-listed from quant-ph
Post-selected Criticality in Measurement-induced Phase Transitions
Dolly Nambi, Kabir Khanna, Andrew Allocca et al. (+4 more)
Information-theoretic phase transitions, such as the measurement-induced phase transition (MIPT), characterize the robustness of
quantum dynamics to local monitoring and are naturally formulated in terms of trajectories conditioned on typical measurement outcomes, which are naively accessible only through postselection. Here, we implement forced measurements to investigate how explicit postselection alters the nature of the transition. We find that postselection fundamentally alters the universality class by reweighting trajectories that are otherwise rare. In particular, we obtain a correlation-length exponent $\nu\approx 2.1$ larger than that of the standard MIPT and a negative effective central charge $c_\mathrm{eff}\approx -0.35$. We also compare the postselected MIPT to the
entanglement transition of random tensor networks, and demonstrate that their universality class is the same. This setup further allows time-periodic, translationally invariant
circuits with postselected weak measurements. In both models, we find that an on-site dimension of at least 3 (qutrits but not
qubits) is necessary to induce a transition.
Read the full abstract ▾
All authors Dolly Nambi, Kabir Khanna, Andrew Allocca, Thomas Iadecola, Ciarán Hickey, Romain Vasseur, Justin H. Wilson
Statistical Mechanics · Cross-listed from quant-ph
Redundancy from Subsystem Thermalization
Xiangyu Cao and Zohar Nussinov
In the theory of decoherence, redundancy is the correlation between a
quantum system and fractions of the environment. It underlies the emergence of classical behavior. We show that redundancy can persist despite thermalizing dynamics in the environment. This follows an initial broadcasting interaction that changes the density of a conserved quantity. The mutual information between the system and a fraction of the environment is estimated using the large deviation principle governing subsystem thermalization.
Read the full abstract ▾
Mesoscale and Nanoscale Physics · Cross-listed from quant-ph
Entanglement advantage in sensing power-law spatiotemporal noise correlations
Yu-Xin Wang, Anthony J. Brady, Federico Belliardo et al. (+1 more)
Noise sensing underlies many physical applications including tests of non-classicality, thermometry, verification of correlated phases of
quantum matter, and characterization of criticality. While previous works have shown that
quantum resources such as
entanglement and squeezing can enhance the sensitivity in estimating deterministic signals, less is known about the
entanglement advantage in sensing correlated
stochastic signals (noise). In this work, we compute the fundamental sensitivity limits of
quantum sensors in probing spatiotemporally correlated noise. We first prove the fundamental
quantum limits in sensing spatially correlated Markovian noise using entangled and unentangled sensors, respectively. Focusing on power-law spatial noise correlations, which naturally arise in condensed matter systems with long-range interactions and/or near criticality, we further derive a scalable
entanglement advantage when the power-law decays slowly. Then, considering a target signal with a $1/f^{p}$-type spectrum, we demonstrate that non-Markovianity may entirely modify the nature of
entanglement advantage in estimating spatial noise correlations. Our protocols can be implemented using state-of-the-art
quantum sensing platforms including solid-state defects, superconducting
circuits, and neutral atoms.
Read the full abstract ▾
All authors Yu-Xin Wang, Anthony J. Brady, Federico Belliardo, Alexey V. Gorshkov
Strongly Correlated Electrons
Neural-Network Quantum Embedding Solvers for Correlated Materials
Agnes Valenti, Ina Park, Antoine Georges et al. (+2 more)
Quantum impurity solvers are the computational bottleneck of
quantum embedding approaches to correlated materials, such as dynamical mean-field theory (DMFT). We show that neural networks trained on synthetic, material-agnostic data learn the
impurity mapping from hybridization functions and local interactions to Green's functions with quantitative accuracy for both model systems and real materials, providing fast solvers for single- and multi-orbital models.
Benchmarks against numerically controlled
quantum Monte Carlo show that the method reproduces the Mott transition, multi-orbital phase diagrams of Hubbard-Kanamori models, and the electronic properties of SrVO$_3$ and SrMnO$_3$. The learned solvers achieve orders-of-magnitude speedup and can initialize controlled calculations, dramatically accelerating DMFT while preserving accuracy.
Read the full abstract ▾
All authors Agnes Valenti, Ina Park, Antoine Georges, Andrew J. Millis, Olivier Parcollet
Strongly Correlated Electrons
AC Fingerprints of 2D Electron Hydrodynamics: Superdiffusion and Drude Weight Suppression
Davis Thuillier and Thomas Scaffidi
Clean two-dimensional
Fermi liquids are now known to exhibit an intermediate tomographic regime, between ballistic and Navier–Stokes transport, caused by the anomalously slow relaxation of parity-odd multipolar deformations of the
Fermi surface. Here we show that this anomaly extends to the dynamical realm. Starting from a microscopic numerical evaluation of the linearized electron–electron collision operator, we find that the finite-frequency nonlocal conductivity is controlled at low frequency by a single hydrodynamic pole, $\sigma(q,\omega)=\mathcal{D}(q)/(i\omega+\eta_\star q^z)$, with dynamical exponent $z=4/3$ and superdiffusive viscosity $\eta_\star$. Remarkably, the pole residue itself is scale dependent and obeys $\mathcal{D}(q)\sim q^{-\alpha}$ with $\alpha=1/3$, so the dynamical properties are described by two separate exponents rather than one. We interpret the residue suppression using a Krylov-chain description of current relaxation: as $q$ increases, the longest-lived quasinormal mode ceases to be a nearly pure current excitation and spreads over higher odd angular harmonics. Finally, we show that AC transport in narrow channels provides a direct experimental probe of these phenomena.
Read the full abstract ▾
Materials Science
LLM-Driven Discovery of High-Entropy Catalysts via Retrieval-Augmented Generation
AI Scientists, Xinyi Lin, Danqing Yin et al. (+1 more)
CO2 reduction requires efficient catalysts, yet materials discovery remains bottlenecked by 10-20 year development cycles requiring deep domain expertise. This paper demonstrates how large
language models can assist the catalyst discovery process by helping researchers explore chemical spaces and interpret results when augmented with
retrieval-based grounding. We introduce a
retrieval-augmented generation framework that enables GPT-4 to navigate chemical space by accessing a database of 50,000+ known materials, adapting general-purpose
language understanding for high-throughput materials design. Our approach generated over 250 catalyst candidates with an 82% thermodynamic stability rate while addressing multi-objective constraints: 68% achieved <$100/kg cost with metallic conductivity (band gap<0.1eV) and mechanical stability (B/G>1.75). The best-performing Fe0.2Co0.2Ni0.2Ir0.1Ru0.3 achieves 0.285V limiting potential (25% improvement over IrO2), while Cr0.2Fe0.2Co0.3Ni0.2Mo0.1 optimally balances performance-cost trade-offs at $18/kg. Volcano plot analysis confirms that 78% of LLM-generated catalysts cluster near the theoretical activity optimum, while our system achieves 200x computational efficiency compared to traditional high-throughput screening. By demonstrating that
retrieval-augmented generation can ground AI creativity in physical constraints without sacrificing exploration, this work demonstrates an approach where natural
language interfaces can streamline materials discovery workflows, enabling researchers to explore chemical spaces more efficiently while the LLM assists in result interpretation and hypothesis generation.
Read the full abstract ▾
All authors AI Scientists, Xinyi Lin, Danqing Yin, Ying Guo
Statistical Mechanics
Non-Thermal Aging of Supercooled Liquids in Optical Cavities
Muhammad R. Hasyim, Arianna Damiani and Norah M. Hoffmann
Aging is a hallmark of disordered materials such as glasses, plastics, and pharmaceuticals, where it often limits long-term stability and performance. In practice, aging is controlled through global parameters like temperature or pressure, which act uniformly on the entire system. Here we introduce a fundamentally different approach, using light confined in optical cavities as a precise and selective tool to guide aging dynamics. We show that a supercooled
liquid coupled to an optical cavity undergoes non-thermal aging, where aging is induced by light without a thermal quench. Light selectively pumps fast vibrational modes while the bath temperature remains unchanged, reshaping the slow structural dynamics of the
liquid. The cavity-coupled
liquid thereby behaves as if it were structurally colder than its surroundings. Exploiting this effective structural cooling together with the timescale separation, we introduce cavity configurational feedback ($\mathrm{C^2F}$) cooling, which uses cavity coupling to reach progressively lower structural temperatures. Our results establish a connection between glass physics and strong light-matter interactions and open a new route toward optical control of aging, glass formation, and nonequilibrium materials dynamics.
Read the full abstract ▾
Strongly Correlated Electrons · Cross-listed from quant-ph
Benchmarking quantum simulation with neutron-scattering experiments
Yi-Ting Lee, Keerthi Kumaran, Bibek Pokharel et al. (+7 more)
Realistic simulation of
quantum materials is a central goal of
quantum computation. Although
quantum processors have advanced rapidly in scale and fidelity, it has remained unclear whether pre-fault-tolerant devices can perform quantitatively reliable material simulations. We demonstrate that a superconducting
quantum processor operating on up to 50
qubits can already produce meaningful, quantitative comparisons with inelastic
neutron-scattering measurements of KCuF$_3$, a canonical realization of a gapless Luttinger
liquid system with a strongly correlated ground state and a spectrum of emergent spinons. The
quantum simulation is enabled by a
quantum-classical workflow for computing dynamical structure factors (DSFs). The resulting spectra are benchmarked against experimental measurements using multiple metrics, highlighting the impact of
circuit depth and
circuit fidelity on simulation accuracy. Finally, we extend our simulations to a 1D XXZ Heisenberg model with next-nearest-neighbor (NNN) interactions and a strong anisotropy, producing a gapped excitation spectrum, which could be used to describe the CsCoX$_3$ compounds above the Néel temperature. Our results establish a framework for computing DSFs for
quantum materials in classically challenging regimes of strong
entanglement and long-range interactions, enabling
quantum simulations that are directly testable against laboratory measurements.
Read the full abstract ▾
All authors Yi-Ting Lee, Keerthi Kumaran, Bibek Pokharel, Allen Scheie, Colin L. Sarkis, David A. Tennant, Travis Humble, André Schleife, Abhinav Kandala, Arnab Banerjee
Soft Condensed Matter
Nonequilibrium energetics of sensing and actuation by a smart active particle
Luca Cocconi, Benoît Mahault and Lorenzo Piro
Smart active
agents must allocate finite energetic resources across distinct functions, yet the underlying thermodynamic trade-offs remain poorly understood. Here, we introduce a minimal model of a self-steering particle with an internal polarity-cue sensor coupled to an external environmental field, decomposing its steady-state
entropy production rate into locomotion, actuation, and sensing costs. This separation exposes an energetic bookkeeping structure underlying even the simplest form of
embodied navigation. The emergence of Pareto fronts linking energetic expenditure to localisation precision and path-following performance shows that feedback-controlled active motion is constrained by quantitative thermodynamic bounds that persist across distinct task geometries.
Read the full abstract ▾
Mesoscale and Nanoscale Physics
Probing the Penetration Depth of Topological Surface States by Magnetic Impurity Scattering in V-doped Sb$_2$Te$_3$
Yidi Wang, Zeyu Ma, Pengcheng Chen et al. (+11 more)
Topological
insulators host Dirac surface states (SS) protected by time-reversal
symmetry. Inter-surface hybridization can gap the SS and give rise to the
quantum spin Hall effect in films that are sufficiently thin compared to the SS penetration depth. However, quantifying the SS penetration depth typically requires painstaking synthesis of multiple films with varying thickness. Here we introduce a direct method to probe the SS penetration depth in bulk
crystals, by studying the interplay between SS and
magnetic impurities in \SVT. Using scanning tunneling microscopy and spectroscopy, we find that even sparse
magnetic impurities ($\lesssim0.25\%$ vanadium) can gap the Dirac SS. However, a single V
impurity induces only localized states, and does not form an
impurity band, so the gapped Dirac dispersion is preserved away from the
impurity. In high
magnetic fields, we observe an energy shift of the $0^\text{th}$ Landau level and a suppression of quasiparticle lifetime at the Dirac point, indicating \newtext{
magnetic} scattering of the SS. Crucially, by employing V
impurities at different depths as precise scattering probes, we reveal the SS penetration depth on the sub-nanometer scale in a bulk
crystal.
Read the full abstract ▾
All authors Yidi Wang, Zeyu Ma, Pengcheng Chen, Shiang Fang, Yu Liu, Yau Chuen Yam, Christopher Eckberg, Joshua Samuel, Johnpierre Paglione, Mohammad Hamidian, Cyrus Hirjibehedin, Daniel T. Larson, Efthimios Kaxiras, Jennifer E. Hoffman
Mesoscale and Nanoscale Physics
Flat-Band Generation in InAs/GaSb Quantum Wells through Vertically Engineered Heterostructures
Zachery A. Enderson, Jiyuan Fang, Wei-Chen Wang et al. (+8 more)
Quantum materials constitute a novel category of substances wherein
quantum effects and electron-electron (e-e) interactions give rise to unforeseen phenomena on a macroscopic scale. Of particular interest within the realm of
quantum materials are flat bands, which promote heavy conduction electrons and enhance e-e correlation effects. While the engineering of such flat bands has been demonstrated in
graphene and two-dimensional transition metal dichalcogenides moiré superlattices and in lithography defined
semiconductor moiré superlattices, conventional tear-and-stack fabrication methods face challenges due to inevitable twist-angle disorder, strain, and relaxation effects, leading to issues with reproducibility and scalability. Here, we explore the creation and modification of flat bands through vertically engineered III-V
semiconductor heterostructures, without the need for twisting. These artificial
quantum materials offer a reproducible and scalable means for producing high-quality flat-band materials via molecular beam epitaxy growth. Our investigation includes magnetotransport and infrared magneto-spectroscopy studies of quad-layer InAs/GaSb
quantum wells, accompanied by k*p band structure calculations, which illustrate the flattening of bands in vertically designed
heterostructures.
Read the full abstract ▾
All authors Zachery A. Enderson, Jiyuan Fang, Wei-Chen Wang, Li Xiang, Mykhaylo Ozerov, Dmitry Smirnov, Zhigang Jiang, Samuel D. Hawkins, Aaron J. Muhowski, John F. Klem, Wei Pan
Soft Condensed Matter
Topological localisation and motility of active knots
Andrea Bonato, Davide Marenduzzo, Enzo Orlandini et al. (+1 more)
Nonequilibrium active
polymers provide a minimal framework to investigate biopolymers such as DNA and chromatin under the action of molecular motors. Here we study active ring
polymers with controlled
topology and show that
knot type qualitatively determines their nonequilibrium behaviour. We find that activity induces opposite localisation responses in different topological families:
torus knots systematically delocalise and inflate, whereas twist
knots tighten and remain localised. We trace this divergent behaviour to the distinct
symmetry properties of their tangent fields, which control the
alignment of active forces along the chain. We show that
topology also governs internal and emergent dynamics. Active
torus knots behave as soft
chiral self-propelled particles exhibiting persistent motion with a well-defined handedness fixed by their topological chirality. In contrast, achiral
knots show no net handedness. The
knot thus acts as a deformable topological quasiparticle whose morphology and propulsion are selected by
topology. These results suggest potential routes toward programmable soft
chiral particles with controllable morphology and emergent motility modes.
Read the full abstract ▾
All authors Andrea Bonato, Davide Marenduzzo, Enzo Orlandini, Giuseppe Negro